Adjective

usage: being effective without wasting time or effort or expense; "an efficient production manager"; "efficient engines save gas"

2. effective, efficient, competent (vs. incompetent)

usage: able to accomplish a purpose; functioning effectively; "people who will do nothing unless they get something out of it for themselves are often highly effective persons..."-G.B.Shaw; "effective personnel"; "an efficient secretary"; "the efficient cause of the revolution"